catalyst at 200°C and 55 atm. The
compound is used extensively in the
rubber industry and in the manufac-
ture of drugs and dyes.
phenylammonium ionThe ion
C 6 H 5 NH 3 +, derived from *pheny-
lamine.
N-phenylethanamideSee ac-
etanilide.
phenylenediamine See di-
aminobenzene.
phenylethene(styrene) A liquid
hydrocarbon, C 6 H 5 CH:CH 2 ; r.d. 0.9;
m.p. –31°C; b.p. 145°C. It can be
made by dehydrogenating ethylben-
zene and is used in making poly-
styrene.
phenyl group The organic group
C 6 H 5 –, present in benzene.
phenylhydrazineA toxic colour-
less dense liquid, C 6 H 5 NHNH 2 , b.p.
240 °C, which turns brown on expo-
sure to air. It is a powerful reducing
agent, made from diazonium salts
of benzene. It is used to identify alde-
hydes and ketones, with which it
forms condensation products called
hydrazones. With glucose and simi-
lar sugars it forms osazones. For
such tests, the nitro derivative 2,4-
dinitrophenylhydrazine (DNP) is
often preferred as this generally
forms crystalline derivatives that can
be identiÜed by their melting points.
Phenylhydrazine is also used to make
dyes and derivatives of *indole.
phenylhydrazonesSee hydra-
zones.
phenylmethanol(benzyl al-
cohol)A liquid aromatic alcohol,
C 6 H 5 CH 2 OH; r.d. 1.04; m.p. –15.3°C;
b.p. 205.4°C. It is used mainly as a
solvent.
phenylmethylamineSee benzyl-
amine.
phenyl methyl ketone (aceto-
phenone)A colourless, crystalline
ketone with an odour of bitter al-
monds, C 6 H 5 COCH 3 , m.p. 20°C. It is
made by treating benzene with
ethanoyl chloride in the presence of
aluminium chloride. It is used as a
solvent and in making perfumes.
3-phenylpropenoic acid See cin-
namic acid.Phillips process A process for
making high-density polyethene by
polymerizing ethene at high pressure
(30 atmospheres) and 150°C. The
catalyst is chromium(III) oxide sup-
ported on silica and alumina.phlogiston theoryA former
theory of combustion in which all
Ûammable objects were supposed
to contain a substance called phlogis-
ton, which was released when the
object burned. The existence of this
hypothetical substance was proposed
in 1669 by Johann Becher, who called
it ‘combustible earth’ (terra pinguis:
literally ‘fat earth’). For example, ac-
cording to Becher, the conversion of
wood to ashes by burning was ex-
plained on the assumption that the
original wood consisted of ash and
terra pinguis, which was released on
burning. In the early 18th century
Georg Stahl renamed the substance
phlogiston(from the Greek for
‘burned’) and extended the theory to
include the calcination (and corro-
sion) of metals. Thus, metals were
thought to be composed of calx(a
powdery residue) and phlogiston;
when a metal was heated, phlogiston
was set free and the calx remained.
The process could be reversed by
heating the metal over charcoal (a
substance believed to be rich in phlo-
giston, because combustion almost
totally consumed it). The calx would
absorb the phlogiston released by the
burning charcoal and become metal-
lic again.409 phlogiston theory
p